Open Bug 2072933 Opened 9 days ago Updated 4 days ago

www.mobile.pasmo.jp - Firefox is not a supported browser

Categories

(Web Compatibility :: Site Reports, defect, P2)

Product:
Web Compatibility
Component:
Site Reports
Platform:
Desktop
Windows 10
Type:
defect

Tracking

(Webcompat Priority:P2, Webcompat Score:5, firefox156 affected, firefox157 affected, firefox158 affected)

Project Flags:
Webcompat Priority P2
Webcompat Score 5
Tracking Flags:
Tracking Status
firefox156 --- affected
firefox157 --- affected
firefox158 --- affected

People

(Reporter: bfarkas, Unassigned)

References

(Depends on 1 open bug,
URL
)

Details

(Keywords: webcompat:needs-contact, webcompat:needs-sitepatch, webcompat:site-report, Whiteboard: [webcompat-source:web-bugs][autowebcompat:processed][autowebcompat:repro-success])

User Story

autowebcompat-repro-status:success
autowebcompat-repro-chrome-mask-fixed:true
autowebcompat-repro-channels:nightly,stable,esr
autowebcompat-repro-report-os:all
platform:windows,mac,linux,android
impact:blocked
configuration:general
affects:all
branch:release
diagnosis-team:webcompat
user-impact-score:200

Attachments

(3 files)

Not a supported browser - Nightly vs Chrome
268.89 KB, video/mp4
Details
Reproduction script generated by autowebcompat bot
2.93 KB, text/javascript
Details
Screenshot generated by autowebcompat bot
31.02 KB, image/png
Details

Environment:
Operating system: Windows 10
Firefox version: Firefox 155.0 / Firefox Nightly 158.0a1 (2026-09-16)

Steps to reproduce:

  1. Access: https://www.mobile.pasmo.jp/
  2. Observe the page

Expected Behavior:
The authentication modal is displayed

Actual Behavior:
"This site cannot be used because the screen may not be displayed correctly in your browser." page is displayed

Notes:

  • Reproduces regardless of the status of ETP
  • Reproduces in firefox-nightly, and firefox-release
  • Does not reproduce in chrome

Created from https://github.com/webcompat/web-bugs/issues/235049

Since nightly and release are affected, beta will likely be affected too.
For more information, please visit BugBot documentation.

status-firefox157: --- → affected
Whiteboard: [webcompat-source:web-bugs] → [webcompat-source:web-bugs][autowebcompat:processed]
User Story: (updated)
Whiteboard: [webcompat-source:web-bugs][autowebcompat:processed] → [webcompat-source:web-bugs][autowebcompat:processed][autowebcompat:repro-success]

In Firefox, https://www.mobile.pasmo.jp/ serves an unsupported-browser notice titled "注意事項" stating the site cannot be used because it may not display correctly in your browser, blocking access to the login form. Chrome instead shows the normal "ログイン" page with the email/password authentication form. This is a user-agent-based block that steers Firefox users away.

User Story: (updated)
Severity: -- → S2
User Story: (updated)
Webcompat Priority: --- → P2
Webcompat Score: --- → 6
Depends on: firefox-not-supported
Keywords: webcompat:needs-contact, webcompat:needs-sitepatch
Priority: -- → P2
Webcompat Score: 6 → 5
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